<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        .container {
            width: 1400px;
            margin: 0 auto;
        }

        .header {
            height: 80px;
            background-color: #abcdef;
        }

        .nav {
            margin-top: 10px;
            height: 80px;
            background-color: #abcdef;
        }

        .main {
            height: 300px;
            margin-top: 10px;
        }

        .left {
            float: left;
            width: 900px;
            height: 300px;
            background-color: #abcdef;
        }

        .right {
            float: right;
            width: 480px;
            height: 300px;
            background-color: #abcdef;
        }
        .footer{
            margin-top: 10px;
            height: 30px;
            background-color: #abcdef;
        }
    </style>
</head>
<body>
<div class="container">
    <div class="header">网站头部</div>
    <div class="nav">网站导航</div>
    <div class="main">
        <div class="left">主要内容</div>
        <div class="right">侧边栏</div>
    </div>
    <div class="footer">底部</div>
</div>
</body>
</html>